1. Field of the Invention
The present invention relates to a method and apparatus for peeling a protective tape adhered to a wafer.
2. Background Art
A need exists to reduce the size of semiconductor electronic devices, as well as to increase their functionality and reduce their power consumption. There is a practice of grinding down the thickness of a wafer in order to reduce the size of the semiconductor electronic devices. When a wafer is ground to a reduced thickness, a protective tape is attached to the wafer surface for protection. The ground wafer is subjected to subsequent processes without removing the protective tape, which tape serves to increase the strength of the wafer. That is, the protective tape also enhances the strength of the wafer, allowing safe handling of the wafer. This protective tape is eventually peeled off or removed by a protective tape peeling apparatus. Specifically, a peeling adhesive tape is attached to the protective tape and is pulled away from the wafer, thereby peeling the protective tape with the peeling adhesive tape thereon from the wafer.
When the patterns on the wafer surface have little or no steps, the adhesion between the wafer surface and the protective tape is high. This means that the protective tape may have lower adhesion to the peeling adhesive tape than to the wafer surface. It has been found that this may result in the peeling adhesive tape peeling away from the protective tape when the peeling adhesive tape is pulled away from the wafer, thus preventing the removal of the protective tape from the wafer surface. In order to solve this problem, a method is proposed in which the protective tape is peeled off while the portion of the tape extending over the notch of the wafer is lifted away from the wafer surface by stress applying means.
It should be noted, however, that the protective tape attached to the wafer surface may not extend exactly to the peripheral edge of the wafer. For example, the protective tape may be attached only to a radially inner portion of the wafer surface. In such cases, there is only a very small overlap between the protective tape and the notch of the wafer, making it impossible to lift the overlapping portion of the protective tape away from the wafer surface by stress applying means.
Further, the protective tape may be attached to the wafer surface so that it extends outwardly beyond the peripheral edge of the wafer. In such cases, the protective tape cannot be sufficiently raised by pushing the portion of the protective tape overlapping the notch of the wafer by stress applying means. Thus, it has been found that the protective tape may not be able to be removed from the wafer if the tape extends short of the peripheral edge of the wafer (i.e., it does not fully cover the peripheral portion of the surface of the wafer) or if the tape extends outwardly beyond the peripheral edge.